A new breast cancer vaccine tested in a clinical trial at the University of Texas MD Anderson Cancer Center boosted survival rates in patients with elevated levels of a protein associated with cancer growth, a new study shows.
The findings, presented at the American Society of Clinical Oncology's Breast Cancer Symposium in San Francisco, show promise for combating aggressive forms of recurrent breast cancer with a vaccine paired with an immunotherapy drug.
The vaccine candidate, dubbed GP2, is designed to use the body's immune system to destroy cancer cells by stimulating CD8+ cells in the body, commonly known as "killer" or "toxic" T cells.
Pairing GP2 with an immune stimulant known as granulocyte-macrophage colony-stimulating factor, researchers tested the combination therapy in 190 patients with varying levels of HER2, a protein associated with cancer growth. In about 20% to 25% of breast cancers, cancer cells produce more HER2 than normal.
One group of women received the vaccine and immunotherapy drug once monthly for 6 months, followed by four cycles of booster shots administered every 6 months for nearly three years.
The survival rate was 94% among patients who completed the vaccine series compared to 85% who did not get GP2 and only received the immunotherapy drug.
While that may not seem like a huge increase in survival rates, results in women with the highest expression of HER2--called HER2 +3--were even more encouraging. In this group, women received Roche's ($RHHBY) Herceptin (trastuzumab) as part of the standard of care prior to receiving the vaccine. In these women, there were no cases of cancer recurrence and all women survived, indicating that the vaccine may be most effective in patients with a higher than normal level of HER2.
"The ultimate goal is to develop a preventative tool that will minimize the risk of recurrence in women who have already had breast cancer and for whom standard therapies have failed," said principal investigator Dr. Elizabeth Mittendorf, associate professor of surgical oncology at the University of Texas MD Anderson Cancer Center, in a statement.
Generex subsidiary Antigen Express is working on a similar breast cancer vaccine, called AE37, which has shown similar success in boosting immune response and improving recurrence rates in triple-negative breast cancer patients. Another candidate, Galena Biopharma's ($GALE) NeuVax, is being tested internationally in a Phase III clinical trial.
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